Actuator assemblies have been known for dispensing soap and other materials in washing machines and dishwashers. In the case of dishwashers, a soap dispenser in the door is operated by electrical control of a resistive heater to heat a thermally responsive actuator.
Actuators of the type which utilize wax, or another thermally expansible material are disclosed in U.S. Pat. Nos. 2,368,181 and 4,441,317.
Such actuators develop large forces over a short stroke distance such as one-quarter inch. When used in an actuator assembly, there is a technical problem in restraining the actuator and reaction devices, such as a plunger return spring, located within the actuator casing. Typically, these casings are made of polyester or another synthetic material.
In one prior known device, the actuator is held inside two casing sections, but due to the forces developed within the housing and a relatively stiff return spring, undue stress may be placed on the connectors which are used to hold the two casing sections together. This can occur in assembly or after a number of operating cycles, which are typically accompanied by moderate to strong vibrations.
It is one object of the present invention to improve on prior casing designs, so the resulting item is easy to assemble in manufacturing, and its connecting members are not subjected to forces during assembly and operation which would cause the casing sections to separate.